A process of preparing acetaldehyde



Patented Mar. 23, 1937 UNITED STATES A PROCESS OF PREPARING AOETALDEHYDE FROM ACETYLENE Paul Both, Heinrich Elvert, and Franz Steinberger, Frankfort-on-the-Main-Hochst, Germany,

assignora to I. 'G. Farbenindustrie Aktiengesellschalt, Frankfort on the Main,

Germany No Drawing. Application February 27, 1934,

Serial No. 713,180. 26, 1932 2 Claims.

The present invention relates to a process of preparing acetaldehyde from acetylene.

The publications of Erdmann and Kiithner in Zeitschrift fiir anorganische Chemie (l898) vol. 3 18, page 55, have disclosed that acetaldehyde is formed by causing acetylene to pass into boiling. dilute sulfuric acid containing mercury sulfate. Later on, it has been found that this reaction occurs relatively slowly at boiling temperature; more rapidly, however, at an average temperature of between 60 C. and 80 vC. The use of such a temperature is described among others in German Patents Nos. 425,665, 518,290 and 517,893. In German Patent No. 293,070, too, 5 there is described a working temperature of about 75 C.; in that process, however, dilute acids containing metallic mercury and an oxidizing agent, such as ferric sulfate are used.

We have now found that in the presence of a catalyzer liquid such as is described in German Patent No. 293,070 the reaction takes place considerably more rapidly at as high a temperature as possible, that is a temperature near the boiling point, than at the temperatures of medium height hitherto used. Already with a small mercury concentration a high efficiency is to be noticed. By the term "temperatures near the boiling point there are to be understood the temperatures between 92 C. and the boiling point possessed by the catalyzer liquid during the circulation of the gas current, this boiling point being included. In most cases it will be advisable to maintain the temperature at 95 C. Since the use of a temperature of medium height a C.) has been found to be advantageous when employing a dilute acid containing mercury sulfate, the result above described is surprising,

namely that Just at temperatures near the boil- In Germany November ing point an improved effect is obtained when employing a dilute acid containing metallic mercury and an oxidizing agent as the catalyzer liquid.

The following example serves to illustrate the invention, but it is not intended to limit it thereto:

A reaction tower is filled with 1400 cc. of dilute sulfuric acid containing ferric sulfate and 50 grams of mercury and a gas current of about 120 liters of acetylene is pressed therethrough every hour. If the temperature is maintained at C., 80 liters of acetylene are transformed into acetaldehyde in the course of 6 hours, at C. there are transformed 94 liters and at 98 C., that is the boiling point of the solution in the circulating current of gas, 158 liters of acetylene are converted into acetaldehyde.

It is advisable to reconduct in known manner the nonconverted acetylene into the cycle of the reaction after the acetaldehyde formed has been obtained.

We claim:

1. The process of preparing acetaldehyde, which comprises conducting acetylene into a dilute acid containing metallic mercury and an oxidizing agent while maintaining the temperature between 92 C. and the boiling point of the reaction liquid.

2. The process of preparing acetaldehyde, which comprises conducting acetylene into a dilute acid containing metallic mercury and an oxidizing agent while maintaining the temperature at about C.

PAUL ROTH.

HEINRICH ELVERT. FRANZ S'I 'EINBERGER. 

